How did Greeks get so smart?

The Greek Empire was a very rich empire, which meant that there were lots of wealthy people. These wealthy people employed servants to take care of everything for them, and so the wealthy people had a lot of spare time. They spent this spare time thinking, making them known as Greek Philosophers. Because they thought about things so much, they made great advances, especially in medicine (for example, Hippocrates and the theory of the four humours).